1. Field of the Invention
The present invention generally relates to a pointing device that can designate a desired location on a display screen, and more particularly, to a pointing device that can perform various input operations, an information display system, and an input method utilizing the pointing device.
2. Description of the Related Art
A pointing device that can move a cursor or a pointer in any direction over the 360 degrees on a screen has been developed as a device for moving a cursor or a pointer displayed on the display screen of a portable terminal or the like.
The structure and the operating principles of a pointing device that utilizes variations in magnetism to move a cursor in any direction over the 360 degrees on a screen are described below.
A pointing device 1 shown in FIG. 1 utilizes variations in magnetism, and includes a magnet 2 that is housed in a housing 4 and cooperates with an operating unit (not shown) and Hall elements 3 that detect a tilt or a movement of the magnet 2. On the housing 4 that houses the magnet 2, a key top unit 5 is provided to cover the housing 4. The key top unit 5 is vertically movable and is supported by springs 6.
The Hall elements 3 are devices that convert a magnetic field into voltage and output the voltage. The Hall elements 3 are arranged symmetrically with respect to a predetermined reference point on a printed board 7, as shown in FIG. 2. For example, a Hall element (+X direction) 10 and a Hall element (−X direction) 11 are arranged in the X direction, and a Hall element (+Y direction) 12 and a Hall element (−Y direction) 13 are arranged in the Y direction.
The magnet 2 has a cylindrical shape, as shown in FIG. 2, and generates a magnetic field vertically with respect to the bottom surface. In a non-operating state, the magnet 2 is at a uniform distance from each of the Hall elements 10, 11, 12, and 13. As the magnet 2 is located at the same distance from the Hall elements 10, 11, 12, and 13, the magnetic fields applied to the respective Hall elements 10, 11, 12, and 13 are substantially the same. Accordingly, the voltages that are output from the Hall elements 10, 11, 12, and 13 are also uniform.
When the magnet 2 is operated and is then tilted or moved, each of the magnetic fields applied to the Hall elements 10, 11, 12, and 13 varies. As a result, the voltages that are output from the Hall elements 10, 11, 12, and 13 also vary. If the magnet 2 is tilted or moved in the positive X direction, the output voltage of the Hall element (+X direction) 10 becomes greater than the output voltage of the Hall element (−X direction) 11.
In accordance with the variations in the outputs of the Hall elements 10, 11, 12, and 13, a signal that can move the target object in any desired direction at a desired speed on the display screen can be calculated.
The pointing cursor control device disclosed in Japanese Unexamined Patent Publication No. 6-289996 refers to a lookup table stored in a memory, and then extracts the target coordinates of the neighboring object located in the direction of moving the cursor. A control operation is then performed to move the cursor immediately to the location represented by the extracted coordinates of the neighboring object.
With the above pointing device, the cursor can be moved in any direction over the 360 degrees on the screen. However, more complicated input operations may be necessary, depending on the application. More specifically, it is necessary to perform a pointing operation in accordance with the application screen. For example, the information as to the location of the pointing device is not necessary on the menu selecting screen, and the cursor needs to be moved only in limited directions.
Japanese Unexamined Patent Publication No. 6-289996 discloses the technique of improving the operability of the pointing device, but does not disclose the technique of performing various input operations with the pointing device.